The present technique relates to a range switching device for switching between ranges according to an operation performed by a driver, the ranges including a parking (P) range, a neutral (N) range, a drive (D) range, and a reverse (R) range, and specifically relates to a range switching device that uses a shift-by-wire method in which a range switching operation performed by the driver is transmitted via an electric signal.
Conventional examples of range switching devices using a shift-by-wire method include a range switching device that transmits a range switching operation of a driver to solenoid valves via an electric signal and switches a range switching valve by operating the solenoid valves.
It has been proposed to configure such a range switching device so as to have a parking switching valve that switches between a parking release state and a parking state, the parking release state being achieved by supplying a hydraulic pressure to a parking device, and the parking state being achieved by supplying no hydraulic pressure to the parking device. (See Japanese Patent Application Publication No. 2014-196771, which had not been published at the time of filing an original application.) In a device described in Japanese Patent Application Publication No. 2014-196771, for example, even if a valve sticks during switching from the parking release state to the parking state, an input port to which the hydraulic pressure to be supplied to the parking device is input and an output port from which the input hydraulic pressure is output to the parking device are allowed to communicate with a drain port from which the hydraulic pressure is drained, so that the supply of the hydraulic pressure to the parking device is blocked. Thereby, the parking device is switched from the parking release state into the parking state.